Catalyst for the oxidation of olefins to unsaturated aldehydes and acids

ABSTRACT

MONOLEFINS SUCH AS PROPYLENE AND ISOBUTYLENE ARE CONVERTED TO THE CORRESPONDING UNSATURATED ALDEHYDES AND CARBOXYLIC ACIDS IN THE PRESENCE OF A CATALYST OF THE COMPOSITION:   NI(0-20)CO(0-15)FE(0.1-7)BI(0.1-4)P(0.1-2)MO120(35-85)

United States Patent Office 3,576,764 Patented Apr. 27, 1971 U.S. Cl. 252-437 5 Claims ABSTRACT OF THE DISCLOSURE Monoolefins such as propylene and isobutylene are converted to the corresponding unsaturated aldehydes and carboxylic acids in the presence of a catalyst of the composition:

This is a continuation-in-part of application Ser. No. 487,611 filed Sept. 15, 1965, now U.S. Pat. 3,454,630.

This invention relates to the production of useful oxygen-containing substances including unsaturated aldehydes and unsaturated carboxylic acids by the oxidation of olefins such as propylene and isobutylene with molecular oxygen or air in the presence of a novel catalyst corresponding to the empirical formula:

Ni Co Fe Bi P Mofi wherein a is 0 to 20, -b is 0 to 15, a plus b equals 2 to 20, c is 0.1 to 7, d is 0.1 to 4, e is 0.1 to 2, f is about 12 and g is 35 to 85.

According to the present invention the catalyst which is employed in a vapor phase catalytic oxidation reaction increases the total conversion to the desired useful products including unsaturated aldehydes and acids without excessive oxidation of the olefins to undesired higher oxidation products of carbon such as carbon monoxide and carbon dioxide.

The process of this invention will now be considered in more detail in regard to the specific desired products, namely, unsaturated aldehydes and unsaturated carboxylic acids.

In the present specification the following definitions are employed:

Mols of olefin converted Conversion (percent)= Mols of olefin fed X 100 Selectivity (percent) Mols of aldehyde or acid obtained 100 Mols of olefin converted Single pass yield (percent) Mols of aldehyde or acid obtained Mols of olefin fed ConversionXselectivity UNSATURATED ALDEHYDES reactor was converted to acrolein, 19% by weight of the propylene was converted to acrylic acid, which amounts to a yield of about of useful products in a single pass of propylene over the catalyst.

The processes for the production of unsaturated aldehydes by the catalytic oxidation of olefins with air or molecular oxygen over the catalyst containing the oxides of bismuth, molybdenum and phosphorus has been previously described in U.S. Pat. 2,941,007. The same process carried out over a catalyst comprised of the oxides of iron, bismuth, phosphorus and molybdenum has been previously disclosed in German Pat. No. 1,125,901 to Knapsack, A. G. Neither of these prior art catalysts contain nickel oxide and cobalt oxide and in this respect the present catalyst compositions are clearly distinguished from those of the prior art.

The inclusion of nickel oxide or cobalt oxide or mixtures thereof in the catalysts embodied herein produces a very high yield of acrolein from propylene. It is apparent that this catalyst is of great commercial value as the following description will indicate.

According to the process of U.S. Pat. 2,941,007, 56.9% by Weight of propylene fed to the reactor is consumed in a single pass over the catalyst and 71.8% of this propylene consumed is converted to acrolein and most of the remainder of the propylene consumed is converted to carbon monoxide and carbon dioxide. The highest single pass yield of acrolein based on the total propylene fed in the U.S. Pat. 2,941,007 is 41%.

In the process of German Pat. No. 1,125,901, 70% of the propylene fed in a single pass over the catalyst is consumed and of this 84% is converted to acrolein. Thus, an overall single pass conversion of propylene to acrolein of 59% is described in the German patent.

In vapor phase catalytic reactions it is generally found that as conversion of the reactants is increased there is a decrease in selectivity so that in the prior art vapor phase oxidation of propylene to acrolein, the single pass conversion to acrolein is usually not very high.

In marked contrast to the prior art processes, in a representative example in the present invention, of the propylene fed in a single pass over the catalyst is consumed and 75% of the propylene consumed is converted to acrolein. Thus, an overall conversion of propylene to acrolein of 71% is obtained in a single pass in the process of this invention. This is indeed unobvious and unexpected in view of the prior art.

When vapor phase catalytic oxidation reactions of the type embodied herein are carried out beyond the point where the total conversion is specific to the catalyst, the production of undesired carbon monoxide and carbon dioxide usually increases and the overall yield of the desired product, such as acrolein, decreases correspondingly.

In the process of the present invention the production of carbon monoxide and carbon dioxide is minimal and usually only about 2% is converted to carbon monoxide and only about 5% is converted to carbon dioxide while the total conversion of propylene is about 95 This is indeed an unexpected result and it is a very desirable advantage from a commercial standpoint.

In the prior art processes it is necessary to recycle unreacted propylene in order to achieve as high yields of acrolein as those obtained in a single pass in the present invention. In the prior art processes when the unreacted propylene is separated from the reactor efiluent which has been passed over the catalyst once and is fed back to the raw propylene feed, the ultimate conversion increases and therefore the yield of acrolein based on the propylene fed increases. When carried out on a commercial scale, it is clear that the process of the present invention, which produces a very high single pass conversion of the propylene and a high yield of acrolein, does not require the recovery and recycle of propylene. Thus, the present process has a decided advantage over the prior art processes in plant construction and operation costs.

UNSATURATED CARB OXYLIC ACIDS Furthermore the present invention has special application to the production of unsaturated aliphatic acids such as acrylic acid by the oxidation of propylene with oxygen. Under the proper conditions, extremely high yields of unsaturated aliphatic acids can be obtained directly by the oxidation of olefins.

In one instance, for example, according to the present process, propylene was oxidized at a temperature of 370 C. top roduce a 46% yield of acrylic acid based on propylene fed along with a 15% yield of acrolein. Thus a total yield of useful products of about 61% Was obtained in this experiment. Upon removal of the acrylic acid from the reactor efl luent and recycling acrolein back to the reactor, the yield of acrylic acid becomes greater than 50%.

Many previous attempts have been made to oxidize olefins with molecular oxygen or air directly to unsaturated acids. In all the prior attempts, however, both the conversion and selectivity have been about 50%, and thus in the best attempts to oxidize propylene to acrolein, a yield of about 20% was obtained. If the conversion was increased, excessive oxidation of the propylene to carbon monoxide and carbon dioxide increased and the single pass yield of acrylic acid decreased. Generally speaking, in a vapor phase catalytic oxidation, as the conversion of the feed is increased, the selectivity of desired product decreases and thus a high single pass yield of acrylic acid from propylene has not heretofore been achieved as has been mentioned above.

According to a representative example of the process of this invention, when the single pass conversion of propylene is brought to more than 90% under the proper conditions, the selectivity to acrylic acid and acrolein amounts to about 60% overall and the yield of acrylic acid usually is about 50%. This is indeed unexpected and is highly advantageous from a commercial standpoint.

The present process for preparing unsaturated carboxylic acids such as acrylic acid is advantageous over the prior art two-step production of acrylic acid via acrolein as an intermediate. The plant investment in a commercial operation is considerably less for the present single-step process for converting propylene to acrylic acid and heretofore the best yields of acrylic acid by the two-step method employing acrolein as an intermediate have been only about 20% based on the original feed.

CATALYST The catalyst useful in the process of the present invention is the homogeneous mixture, compound or possibly a complex of some unknown physical or chemical nature made up of the oxides of iron, bismuth, phos phorus, and molybdenum plus nickel oxide or cobalt oxide. The comopsition is conveniently expressed in the following empirical formula:

Nl cO FC Bi P MO O wherein a is to 20, b is 0 to 15, a plus b equals 2 to 20, c is 0.1 to 7, d is 0.1 to 4, e is 0.1 to 2, f is about 12 and g is 35 to 85.

In particular, the preferred catalysts of this invention can be expressed in the following three empirical formulae:

Ni FQ Bl P MO Of wherein a is 3 to 14, b is 1 to 3, c is 1 to 3, d is about 1, e is 12 and f is 45 to 70;

CO FC Bl P MO Of 4 wherein a is 2 to 7, b is 1 to 3, c is 1 to 3, dis about 1, e is 12 and f is 45 to 70; and

Ni Co Fe Bi P Mo O wherein a is smaller than 14, b is smaller than 7, a plus b equals 2 to 20, a and b is not zero, respectively, 0 islto3,dis1to3,eisabout1,fis12andgis45to 70. The first preferred catalyst mentioned above can also be expressed as a composition containing the following components:

Mole percent Nickel phosphomolybdate 2099.8 Iron phosphomolybdate 0.1-40 Bismuth phosphomolybdate 0.1-40

and the more preferred catalyst of this type has the following composition:

Mole Percent Nickel phosphomolybdate -90 Iron phophomolybdate 5-10 Bismuth phosphomolybdate 5-10 The catalyst of this invention is usually prepared by adding phosphoric acid to an aqueous solution of the suitable molybdenum compound such as ammonium molybdate, and then an aqueous solution of a water-soluble iron salt and bismuth salt plus nickel salt, cobalt salt or the mixture thereof is added to the phosphomolybdic acid solution. This preparation, however, may be varied as preferred. For example, an aqueous solution of the suitable molybdenum compound is added to an aqueous solution of a water-soluble salt and then phosphoric acid is added. The resulting slurry is then heated with a carrier, if desired, to remove water and dry the solid cake which forms. The solid cake is then calcined at an elevated temperature in the air. This calcination is useful for making the specific surface area of the catalyst proper and increasing the selectivity.

Suitable water-soluble salts for the preparation of the catalysts of this invention are, for example, nickel nitrate, cobalt nitrate, ferric nitrate and bismuth nitrate. In special cases, agents which form these water-soluble salts, such as the mixture of metal and acid or of metal oxide and acid may be used in place of water-soluble salts. Molybdenum oxide, molybdic acid or phosphomolybdic acid may suitably be used in place of ammonium :nolybdate.

The catalyst embodied herein is particularly effective when deposited upon a carrier. Suitable carriers include silica, silicon carbide and alumina. The carrier may be added as a sol or a gel to the phosphomolybdate slurry before the catalyst is dried. The catalyst is useful in many solid physical forms such as grains and pellets. The catalyst of this invention is suitable for use in a fixed bed reactor or in a fluidized bed reactor.

THE PROCESS CONDITIONS The catalytic oxidation process of this invention is carried out at a temperature of from 250 to 450 C. and at a pressure of from 0.5 to 10 atmospheres absolute, and preferably at a temperature of from 300 to 450 C. at atmospheric pressure. In general, the yield of unsaturated carboxylic acid is favored in the higher reaction temperature ranges, higher ratios of oxygen to olefin and longer contact times and the converse is true of the yields of unsaturated aldehyde.

In the oxidation of propylene by the instant process the contact time of the mixture of propylene and air with the catalyst is usually from 0.1 to 12 seconds and preferably from 0.5 to 8 seconds at one atmosphere pressure.

The feed for the process embodied herein usually requires the presence of from 0.5 to 5 mols of oxygen per mol of propylene. Stated somewhat differently, the preferred mol ratios of ingredients in the gaseous feed mixture are from 4 to 10 moles of air per mol of propylene. It is preferred that water in the form of steam is fed to the reactor along with the gaseous mixture of propylene and air. A large volume of water in the feed elfects a dilution and removal of reaction heat, but water need not be employed if the reaction heat can efliciently be removed. The mole ratio of water per mol of propylene may be in the range of 1 to 20, but a ratio of S to is pre- 6 cooled mass was pulverized, the powder was pelleted and then calcined at 500 C. for six hours. The catalyst was found to have the following empirical formula:

ferred. The feed gas in the instant process may contain 5 EIQMPLES 247 saturated hydrocarbons such as ethane, propane, etc., Table 1 shows some variations of the manufacturing because they are inert and do not effect the oxidation of procedure and the compositions of catalyst in Example the olefins. I, and the procedure is carried out in the same way as that In general, air is used as the source of molecular oxygen 10 of Example I except for the variation in conditions shown in the instant process; however, molecular oxygen per se, in Table 1.

TABLE 1 Nickel Cobalt Ferric Bismuth Ammonium Phosphoric Carrier Example nitrate nitrate nitrate nitrate molybdate acid, 85% S102 Empirical formula of Number (grams) (grams) (grams) (grams) (grams) (grams) (grams) catalyst 21. 6 25. 0 113. 6 6. 3 40. 0 Nit0C0o.aFezBirP1MouOu 21. 6 25. 0 113. 6 1. 26 40. 0 N10000.3F81B11POJM012053 21. 6 25. 0 113. 6 6. 3 40. 0 N110C003F61B11P1M012051 21. 6 25. O 113. 6 3. 1b 40. 0 NimCOo,aFerBirPoeMmzOaa 32. 4 37. 6 170. O 9. O 60. 0 N14 5C04Fe1BiiP M012O54 64. 8 76. 2 170.0 9.0 60. 0 N17COU.5FG2B12PIM012054 32. 6 37. 6 170. 0 9. 0 60. 0 Ni7C02Fe Bi1P1M012O5 21. 6 25. 0 113. 6 3. 16 34. 2 Ni1o,5Fe1Bi1Po M012O50 21. 6 25. 0 113. 6 9. 48 34. 2 N110.5F81B11P1,5M01205a 43. 2 50. O 113. 6 6. 32 40. 0 NimFezBigP Moizoss 65. 8 75. 0 113. 6 5. 1O 60. 0 N14,.4FeaBiaPo8M012O5a 28.0 17.4 113.6 6.32 60.0 Nii2Fe1,sBi PiMo12O5a 21. 6 25. 0 113. 6 6. 32 40. 0 N114F81B11P1M012050 10. 8 37. 5 113. 6 6. 32 40. 0 N110,5F9U.5B11.5P1M012051 32. 4 37. 6 170. 0 9. 00 60. 0 C0eFe1Bi1P1MO12O50 48.6 56.4 170.0 9. 00 60.0 COLBFGIjBiljPlMOl'zO-lfl or mixtures of oxygen and inert gases such as nitrogen, EXAMPLE 18 carbon dloxlde 1 {nay also be P 140 ml. of the catalyst of the empirical formula S1nce the reaction is exothermic, the temperature within the reactor must be regulated in order to control the 10.5 1 1 1 12 57 g?- i iactor belplaced were placed in a reactor 20 mm. in diameter dipped in a 1 m at a Sa as a 1 g molten potassium nitrate bath maintained at about 310 C. g mtrat? g i slflc ml A gaseous mixture composed as follows was passed over S e yle acro eln an acry 1c the catalyst at atmospheric pressure: ac1d by the oxidation process of th1s1nvent1on1s extremely M01 ratio high, but undesired oxidation products such as carbon Propylene 1 dioxide are produced in minimal amounts. Air 7 10 The process of the present invention is further illussteam 6 trated by the following examples.

EXAMPLE I The apparent contact t1me was 2 seconds.

The conversion, single pass yields and selectivities of (A) 163 grams of nickel nitrate were dissolved in products by this reaction are as follows:

ml. of distilled water; 21.6 grams of ferric nitrate were Percent dissolved in 12 ml. of distilled water; 25.0 grams of bis- 45 Conversion '98 muth nitrate were dissolved in 18 ml. of distilled water Selectivity of acrolein 72 containing 2.4 ml. of concentrated nitric acid and all of One pass yield of acrolein 71 the foregoing solutions were combined. Selectivity of acrylic acid 19.8

(B) 113.6 grams of ammonium molybdate were dis- Single pass yield of acrylic acid 19.4

solved in 140 ml of distilled water and 6.32 grams of EXAMPLES 19-40 phosphonc ac1d were then added. 50

Solution B, which was pale yellow in color, was added Table 2 shows some var1at1ons of the oxidat1on process to solution A and to the resulting slurry were added 34.2 of Example 18 and the procedure is carried .out in the grams of silica in the form of an aqueous so]. The resultsame way as that of Example 18 except for the variation ing slurry was dried and heated at 400 C. in air. The in conditions shown in Table 2.

TABLE 2 Reaction conditions Selectivity Single pass yield Feed composition (mol ratio) (percent) (percent) Contact Bath Contime temp. Proversion, Acro- Acrylic Acro- Acrylic Example number Catalyst composition (second) C.) pylene Air Steam percent lein acid lein acid 19 Ni1o 5Fe1B11P1M01zO57 2.0 300 1 10 6 98 72 19.8 71 19.4 20 NirorFerBirPoaMOrzOsa 2. 0 300 1 10 6 89 73. 5 13. 5 65. 3 12. O 21 N110 5Fe1Bi11 1 ,xsMOuOna 2. U 300 1 10 6 84 64. 7 10. 2 54. 4 8. 5 Ni1.1Fe2BnP1Mono55 3.0 310 1 10 6 68.5 8.2 65.0 7.8 N14 .tFeaBiaPmMmzosa 3. 5 320 1 10 6 92 76. 6 5. 1 70. 5 4. 5 N11QFBLIB10JP1MO1105B 8.0 370 1 12 6 15.4 46.3 15.4 46.3 NluFelBilPiMoizoflo 4.1 345 1 11.4 6 74.5 78 8.4 58 6.3 Ni1nFeo 5Bi1.sP1M01zO57 6. 4 320 1 7. 2 6 84. 8 78 10. 8 66 9.2 Nl o FelBiuP Monos'l 0. 7 360 1 9 6 89. l 60. 5 24. 6 53. 9 21. 9 28 Ni1u 5Fe1Bi1P|M012O5-1 1 320 1 9 4 89.4 73.5 16.3 65.4 14.4 29-- N110000JF21B11P1M012051 4. 6 310 1 8 5 95 75 14. 7 71. 0 14, 0 30.. NimCOogFeiBiiPuMO zou 3. 5 315 1 8 5 97 72 15. 0 70. 0 14. 5 31 NiwCOMFelBiiPmMoizosa 6.4 330 1 8 5 83 73 96.0 01.0 8.0 32 LsC04Fe1Bi1P1M012O52 3. 2 350 1 8 5 95 74 18. 0 70. 0 15. 0 33 NC00JFe1Bi1P1M01zO51 8 330 1 10 6 97 17. 4 44. 5 16. 9 43. 2 34 Ni10COo.sFe1Bi1Pu 5M012O50 9 340 1 10 6 83 21.7 47.0 18.0 39.0 35 N14,:1C04F61Bi1P1M012O54 9 340 1 12 6 95 20. 3 44. 0 19. 3 41. 5 36 N17CO0FB2B12P1M012054 7. 5 350 1 10 6 89. 8 76 15 68. 0 13. 5 37 Ni1Co1Fe1Bi1P1M012Osa 7.2 365 1 10 6 98.0 46 27.6 45.0 27.0 38-- C 0F81BllP1M01zO5u 3. 3 330 1 8 5 98 72 16. 7 70. 5 16. 5 30.. COBFBlBilPlMOlZOSO 9 350 1 12 6 90 20 42.2 18.0 38 40 C04 5Fe1 .51311.5P1M012040 8 335 1 10 6 91. 6 71 20. 2 65. 0 18, 6

EXAM I LE 41 140 ml. of the catalyst of the empirical formula were placed in a reactor mm. in diameter immersed in a molten potassium nitrate bath maintained at about A gaseous mixture composed as follows was passed over the catalyst at atmospheric pressure:

Mol ratio Isobutylene 1 Air 1 1 Steam 6 The apparent contact time was 8.6 seconds.

The conversion, single pass yields and selectivities of products by this reaction are as follows:

Percent Conversion 96 Selectivity of methacrolein 37 Single pass yield of methacrolein 35 Single pass yield of methacrylic acid 20 Selectivity of methacrylic acid 21 EXAMPLES 42-44 Table 3 shows some variations of the oxidation process of Example 41 and the procedure is carried out in the same way as that of Example 41 except for the variation in conditions shown in Table 3.

Ni CO Fe Bi P MO O wherein a is 0 to 20, b is 0 to 15, a plus b equals 2 to 20,

c is 0.1 to 7, d is 0.1 to 4, e is 0.1 to 2, f is about 12 and g is to 85.

2. The catalyst of claim 1 on a silica carrier. 3. The catalyst corresponding to the empirical formula:

Ni Fe Bi P Mo O wherein a is 3 to 14, b is 1 to 3, c is 1 to 3, d is about 1, e is 12 and f is to 70.

4. The catalyst corresponding to the empirical formula:

Co Fe Bi P Mo O wherein a is 2 to 7, b is 1 to 3, c is 1 to 3, d is about 1, e is 12 and f is 45 to 70.

5. The catalyst corresponding to Ni CQbFC Bi P MO O the empirical formula:

wherein a is smaller than 14, b is smaller than 7, a plus b equals 2 to 14, a and b are not Zero, respectively, c is 1 to 3, d is 1 to 3, e is about 1, f is 12 and g is 45 to 70.

TABLE 3 Reaction conditions Selectivity Single pass yield Feed composition (percent) (percent) Bath ratio) Contact tem- Con- Meth- Meth- Example time perature Isobuversion, Methacrylic Methacrylic Number Catalyst composition (second) 0.) tylene Air Steam percent acrolein acid acrolein acid 42 Ni1zFei,:Bio,7P1M012Oss 12. 0 00 1 8 3 100 4. 8 32 4. 8 32. 0 43.. NimsFmBirPrMOrzOm 4. O 270 1 15 10 96 37 10 35. 0 9. 44 Ni1oC0n,aFeiBi1P1M0t2051 10. 0 330 1 5 8 15. 2 40. 7 12. 1 32. 5

References Cited UNITED STATES PATENTS 3,087,964 4/1963 Koch et a1. 252435X 3,171,859 3/1965 Sennewald et a1. 252443X 3,264,347 8/1966 Sennewald et a1. 252437X 3,352,905 11/1967 Kerr 252437X PATRICK P. GARVIN, Primary Examiner US. Cl. X.R.

P0405) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,576,764 Dated April 27, 1971 Inventor) Goichi Yamaguchi et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' Column 3: Line 16, "top roduce" should be --to produce-- Column A: Line 19, "phophomolybdate" should be --phosphomolybdate-- Column 5: Line 37, after "such as" insert --carbon monoxide and-- Column 6: Line 13, Table I, Example No. 3, last column "N 00 Fe Bi P MO 0 should be 10 0.3 1 1 0.2 12 53 --N1 CO F8 Bi P MO 0 Column 6: Line 22, lable I, Example No. 12, last column Yl H Ni Fe Bi P MO O should be -Ni F El P MO 0 1.5 3 3 0.8 12 53 Column 6: Line 63, Table II, Example No. 27, second columl II II N1 51 6 3111P114012057 should be --Ni Fe Bi P MO 0 Line 76, Table II, Example No. 40, second column MO should be o 1 P o c 4 S LB 1.5 1 12 1 "co Fe Bi P MO 0 l... 4.5 1.5 1.5 1 12 M9 Signed and sealed this 21st day of September 1971.

(SEAL) Attest:

ROBERT GOTTSCHALK x1 um 1 EDLARD Acting Commissioner of Patent 

